// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_GFX_FONT_LIST_H_
#define UI_GFX_FONT_LIST_H_

#include <string>
#include <vector>

#include "base/memory/ref_counted.h"
#include "ui/gfx/font.h"
#include "ui/gfx/gfx_export.h"

namespace gfx {

class FontListImpl;

// FontList represents a list of fonts and provides metrics which are common
// across the fonts.  FontList is copyable and quite cheap to copy.
//
// The format of font description strings is a subset of that used by Pango, as
// described at
// http://developer.gnome.org/pango/stable/pango-Fonts.html#pango-font-description-from-string
//
// Pango font description strings should not be passed directly into FontLists.
//
// The format is "<FONT_FAMILY_LIST>,[STYLES] <SIZE>", where:
// - FONT_FAMILY_LIST is a comma-separated list of font family names,
// - STYLES is an optional space-separated list of style names (case-sensitive
//   "Bold" and "Italic" are supported), and
// - SIZE is an integer font size in pixels with the suffix "px".
//
// Here are examples of valid font description strings:
// - "Arial, Helvetica, Bold Italic 14px"
// - "Arial, 14px"
class GFX_EXPORT FontList {
public:
    // Parses a FontList description string into |families_out|, |style_out| (a
    // bitfield of gfx::Font::Style values), and |size_pixels_out|. Returns true
    // if the string is properly-formed.
    static bool ParseDescription(const std::string& description,
        std::vector<std::string>* families_out,
        int* style_out,
        int* size_pixels_out);

    // Creates a font list with default font names, size and style, which are
    // specified by SetDefaultFontDescription().
    FontList();

    // Creates a font list that is a clone of another font list.
    FontList(const FontList& other);

    // Creates a font list from a string representing font names, styles, and
    // size.
    explicit FontList(const std::string& font_description_string);

    // Creates a font list from font names, styles and size.
    FontList(const std::vector<std::string>& font_names,
        int font_style,
        int font_size);

    // Creates a font list from a Font vector.
    // All fonts in this vector should have the same style and size.
    explicit FontList(const std::vector<Font>& fonts);

    // Creates a font list from a Font.
    explicit FontList(const Font& font);

    ~FontList();

    // Copies the given font list into this object.
    FontList& operator=(const FontList& other);

    // Sets the description string for default FontList construction. If it's
    // empty, FontList will initialize using the default Font constructor.
    //
    // The client code must call this function before any call of the default
    // constructor. This should be done on the UI thread.
    //
    // ui::ResourceBundle may call this function more than once when UI language
    // is changed.
    static void SetDefaultFontDescription(const std::string& font_description);

    // Returns a new FontList with the same font names but resized and the given
    // style. |size_delta| is the size in pixels to add to the current font size.
    // |font_style| specifies the new style, which is a bitmask of the values:
    // Font::BOLD, Font::ITALIC and Font::UNDERLINE.
    FontList Derive(int size_delta, int font_style) const;

    // Returns a new FontList with the same font names and style but resized.
    // |size_delta| is the size in pixels to add to the current font size.
    FontList DeriveWithSizeDelta(int size_delta) const;

    // Returns a new FontList with the same font names and size but the given
    // style. |font_style| specifies the new style, which is a bitmask of the
    // values: Font::BOLD, Font::ITALIC and Font::UNDERLINE.
    FontList DeriveWithStyle(int font_style) const;

    // Shrinks the font size until the font list fits within |height| while
    // having its cap height vertically centered. Returns a new FontList with
    // the correct height.
    //
    // The expected layout:
    //   +--------+-----------------------------------------------+------------+
    //   |        | y offset                                      | space      |
    //   |        +--------+-------------------+------------------+ above      |
    //   |        |        |                   | internal leading | cap height |
    //   | box    | font   | ascent (baseline) +------------------+------------+
    //   | height | height |                   | cap height                    |
    //   |        |        |-------------------+------------------+------------+
    //   |        |        | descent (height - baseline)          | space      |
    //   |        +--------+--------------------------------------+ below      |
    //   |        | space at bottom                               | cap height |
    //   +--------+-----------------------------------------------+------------+
    // Goal:
    //     center of box height == center of cap height
    //     (i.e. space above cap height == space below cap height)
    // Restrictions:
    //     y offset >= 0
    //     space at bottom >= 0
    //     (i.e. Entire font must be visible inside the box.)
    gfx::FontList DeriveWithHeightUpperBound(int height) const;

    // Returns the height of this font list, which is max(ascent) + max(descent)
    // for all the fonts in the font list.
    int GetHeight() const;

    // Returns the baseline of this font list, which is max(baseline) for all the
    // fonts in the font list.
    int GetBaseline() const;

    // Returns the cap height of this font list.
    // Currently returns the cap height of the primary font.
    int GetCapHeight() const;

    // Returns the expected number of horizontal pixels needed to display the
    // specified length of characters. Call GetStringWidth() to retrieve the
    // actual number.
    int GetExpectedTextWidth(int length) const;

    // Returns the |gfx::Font::FontStyle| style flags for this font list.
    int GetFontStyle() const;

    // Returns the font size in pixels.
    int GetFontSize() const;

    // Returns the Font vector.
    const std::vector<Font>& GetFonts() const;

    // Returns the first font in the list.
    const Font& GetPrimaryFont() const;

private:
    explicit FontList(FontListImpl* impl);

    static const scoped_refptr<FontListImpl>& GetDefaultImpl();

    scoped_refptr<FontListImpl> impl_;
};

} // namespace gfx

#endif // UI_GFX_FONT_LIST_H_
